XC6222 Datasheet, PDF (9/26 Pages) Torex Semiconductor – Reverse Current Protection, 700mA High Speed LDO Regulator

■OPERATIONAL EXPLANATION (Continued)
XC6222
Series
<C_L Auto-Discharge Function>
XC6222B/D series can discharge the electric charge stored in the output capacitor (CL), when a low signal to the CE pin, which
enables the whole IC circuit to be turned off, is inputted via the N-channel transistor located between the VOUT pin and the VSS
pin (cf. BLOCK DIAGRAM). The CL auto-discharge resistance value is set at 530Ω(TYP.). The discharge time of the output
capacitor (CL) is set by the CL auto-discharge resistance (R) and the output capacitor (CL). By setting the time constant of the
CL auto-discharge resistance value [R_DCHG] and the output capacitor value (CL) as τ(τ=C x R_DCHG), the output voltage after
discharge via the N-channel transistor is calculated by the following formula.
V = VOUT(E) x e ^–t/τ, or t=τIn ( V / VOUT(E) )
where
V: Output voltage after discharge
VOUT (E): Output voltage
t: Discharge time
τ: CL auto-discharge resistance R_DCHG×Output capacitor (CL) value C)
<CE Pin>
The entire XC6222 circuitry can be turned off via the CE pin signal. In shutdown mode, output at the VOUT pin will be pulled
down to the VSS level via R1 & R2. However, with the XC6222B series, the CL auto-discharge resistor is connected in parallel to
R1 and R2 while the power supply is applied to the VIN pin. Therefore, time until the VOUT pin reaches the VSS level is shorter.
For the XC6222A/B series, the output voltage becomes unstable, when the CE pin is left open. If this CE pin voltage is set with
the specified voltage range, the logic is fixed and the IC will operate normally. However, the supply current may increase as a
result of shoot-through current in the IC's internal circuitry when a medium voltage is input to the CE pin. With the XC6222C/D
series, when the CE pin is left open, output voltage is fixed to V_SS level.
■NOTES ON USE
1. Please use this IC within the stated absolute maximum ratings. The IC is liable to malfunction should the ratings be
exceeded.
2. Where wiring impedance is high, operations may become unstable due to noise and/or phase lag depending on
output current.
Please wire the input capacitor (CIN) and the output capacitor (CL) as close to the IC as possible.
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